That would be a really cool feature though, those horrible helpline calls telling me they are recording me for their training purposes, then they tell/promise you stuff that they deny later, and surprise that part of the call wasn't recorded. I am well up for instant recording, somebody make it happen. Please

It might be because depending on where you are its illegal to record a conversation without both parties being aware or having a warrant. I know some places only one side needs to be aware though. I would bet no one is willing to open themselves up to liability from such a thing.